1. Field of the Invention
The present invention relates to a transmission mechanism for bicycle and more particularly, to a two-way propelling type transmission mechanism for bicycle, which can be propelled either forwardly or backwardly to move the bicycle, allowing the user to apply force to the pedals through different parts of the soles of the legs.
2. Description of the Related Art
A transmission mechanism for bicycle is known comprising a driving axle, a gear cluster mounted on one end of the driving axle for synchronous rotation, two pedals, two cranks coupled between the two ends of the driving axle and the two pedals. When pedaling the pedals to rotate the cranks forwards, the gear cluster is rotated with the driving axle to move the bicycle forwards. On the contrary, when pedaling the pedals to rotate the cranks backwards, the driving axle is rotated counter-clockwise without moving the gear cluster. Therefore, the driving axle runs idle when the user pedals the pedals backwardly. Thus, the user can propel the pedals to move the bicycle forwards only applying a force through the front part (the toes) of the sole of each leg. The front part of the sole of each leg will become tired and painful soon when pedaling the pedals of the bicycle in this manner.